1. Technical Field of the Invention
The present invention relates to level shifting devices, and more particularly, to level shifting devices which operate at high frequencies, e.g., up to about 2 MHz, and exhibit low power dissipation and good immunity to transient (i.e., common mode) voltages.
2. Relevant Art
Level shifters are basically interface buffers that couple signals referenced to a first signal level into circuits referenced to a completely separate and different second signal level. For example, portions of an integrated circuit (IC) logic device may be connected between a supply voltage VSUPP and a common signal level COM, but the output of the IC must drive another device connected between a power voltage VPWR and a ground GND. Examples of such applications include half-bridge and full-bridge high voltage topologies used in motor drives, lighting ballasts, class-D audio amplifiers and other floating well system topologies.
In some applications, such as class-D amplifiers and plasma panel displays, the level shifter must operate at high frequencies (e.g., up to about 2 MHz) with minimum propagation delays, and must be immune to false operation by common mode transients due to the high switching speeds. And always, with ICS, low power dissipation is an important consideration.
Numerous circuit designs have been proposed to satisfy these requirements, but all are deficient to a greater or lesser degree in one or more respects. Thus a need still exists for a level shifter circuit design which better meets these requirements.